Sense Organ - The Ears ( Finals ) Flashcards
the ear transduces mechanical energy (in the form of sound waves) into electrical energy (in the form of nerve impulses) and transmits information to the brain.
hearing
Parts of ear involved in hearing are:
external, middle and inner ear
delivers information to the brain on position and movement of the head as related to gravitational pull. Only the inner ear is involved
maintain balance
• External ear
– Pinna = ?
– External acoustic meatus = Ear canal
auricle
• External ear
– Pinna = auricle
– External acoustic meatus = ?
Ear canal
Tympanic cavity connects with pharynx via the auditory tube
Middle ear
– Membranous labyrinth within the bony labyrinth
– Functions for both balance and hearing
Inner ear
⚫ portion that is visible externally
⚫ supported by auricular cartilage which is elastic in nature
PINNA OR AURICLE
⚫ rostral surface is concave and caudal contour is convex forming a natural “scoop” for sound waves
Auricular cartilage
⚫ most proximal, strongly curved portion
⚫ portion closest to the head
⚫ conchal cavity
Concha
Concha – has several elevations of cartilage:
⚫ Tragus
⚫ pretragic incisure
⚫ Antitragus
⚫ intertragic incisure
more distal flattened portion of pinna
Scapha
⚫ mainly cartilaginous, but also has a bony portion
⚫ cartilaginous portion represents the tubular lateral portion of auricular cartilage
EAR CANAL
is small tubular piece of cartilage, increases mobility of external ear by joining external ears main portion with its deepest portion
auricular cartilage
Ear canal course is roughly what shape?
“L-shaped”
• Consists of an air-filled tympanic cavity connected with the
nasopharynx via the auditory tube and closed to the outside by the tympanic membrane at the level of the external acoustic meatus
– has a small, dorsal epitympanic recess and
– a large, ventral tympanic bulla
MIDDLE EAR
– thin, semitransparent membrane situated at the lumen of external acoustic meatus
– separates the external ear from the middle ear
– attached to temporal bone by tympanic ring
Tympanic membrane – the eardrum
MIDDLE EAR
• The middle portion of the tympanic cavity contains the three auditory ossicles— what are those three?
– malleus,
– incus, and
– stapes
MIDDLE EAR
• The middle portion of the tympanic cavity contains the three auditory ossicles—
– malleus,
– incus, and
– stapes—and
• what are the two muscles associated with them— ?
– the tensor tympani on the malleus and
– the stapedius on the stapes
THE TYMPANIC CAVITY
• Divided into 3 portions:
– Epitympanic recess
– Tympanic cavity proper
– Tympanic bulla
⚫ smallest most dorsal of the three chambers of tympanic cavity
⚫ contains the auditory ossicles and associated muscles
EPITYMPANIC RECESS
⚫ resemblance to hammer
⚫ largest most lateral adjacent to tympanic membrane
malleus
“handle”, elongated part of malleus, embedded in the fibrous layer of the ear drum
manubrium
Part of malleus that provides insertion point for tensor tympani muscle
tiny hook
Part of malleus that articulates with incus
head
resemblance to anvil
incus
“stirrup”, smallest bone in the entire body
stapes
⚫ midportion region adjoining the tympanic membrane
⚫ midportion of the cavity receives the opening of auditory tube (from nasopharynx) and communicates in the inner ear by way of vestibular (oval) and cochlear (round) windows
TYMPANIC CAVITY PROPER
⚫ houses the cochlea of inner ear
Promontory
(round window)
Cochlear window
(oval window)
Vestibular window
⚫ ventral portion, ventrally expanded “bubble” of bone visible from external surface of skull
⚫ theorized to aid in perception of sounds at both very high and very low ranges
TYMPANIC BULLA